You must be doing something wrong. Hard to tell with so little info. Unzip Supertestmode.zip and place TESTMODE.KEY in the root of an empty FAT32 formatted SD. Best to use a 4GB or 8GB SD. The bootloader isn't very smart.
If you can't boot into TestMode, you're out of luck. But I doubt your unit is totally bricked.
You never said what failed or what you were trying to install. I hope it wasn't Condi's hack mode.

Yes, between speed sensor, knowing whether the vehicle is going forward or reverse, and the inertial guidance (senses turns and even inclines) your GPS's dead reckoning will do a pretty good job estimating your vehicle's position. However it will eventually drift off. Last year while not actually navigating by GPS, I glanced at my map display and saw my car's position was on the wrong side of a river. However the speed and turns matched my driving. When I got home I had to re-position my GPS antenna to a better spot under my cowling - it seems it slipped too close to the firewall.

Here's a link to installation and user's manuals. AVIC-X930BT Manuals
I don't think there's any settings that could cause this. Assuming it was installed correctly (2 separate circuits and fuses - one always hot and one hot with the accessories) then it might be something wrong with the car's ignition switch.

Did you do as II suggested in the other thread? Disconnect the battery for 30 seconds. Get the manual and find the section on Factory Reset. The power recycle resets some things but I don't think it allows you to reset the text language. There is table in the manual that defines 3 methods to reset the unit and what settings get cleared with each method. IIRC, you want to try method 2.

I have no ideas. I don't use the EU firmware since I'm in the US. You should ask this question in the F-Series forum (probably in Hacks/Mods sub-forum). I think the greyed-out language is the one selected. You touch the one you want. You likely need a factory reset to get to that screen. Before doing that, I'd disconnect the battery for 30 seconds.

Did you replace Cardinfo.cif on the SD with the one in my post (that you just quoted)? Since you have an F920bt, you must use that CardInfo.CIF. BTW. it is just a text file so any editor can view/edit it as long as it doesn't do any formatting. Cardinfo.cif must be 300 bytes.

That script is only for when your headunit has been locked and requires a password to boot-up. It is an anti-theft security feature that usually happens when the car's battery is removed (or dies).
It sounds like you want to run the Shortfuse script to allow installing a 2017 map update. That hack disables the validation of a unique password as part of the installation. When the 2017 maps get installed you just enter "PASSWORDPASSWORD" when prompted. Don't get this confused with the password required to unzip the archive after you download it. That one is defined in the first post of the thread.

Too many things going on here.
What password hack? You never said you were locked-out of your headunit. Did it say "Password Removal will start in 5 seconds..."? Maybe you meant the Shortfuse hack? It has a message that says "Installation will start in 5 seconds...".
In either case, the SD must not be write-protected. If you are asking about the update installation password, you can back out by removing the SD and rebooting.
So what are you trying to do? If it is the EU 2017 update, please post questions in that thread.

I personally have no place to host files. I doubt AVIC411 would since they could be held liable by Pioneer.
Are you saying there will be a 2019 update for the x930? Any idea when?
I stay out of cleaning-up condi-hackmode messes. It could be as simple as deleting the replacement navi.exe and renaming the old (saved) one back. Or, if you are just trying to recover from a failed install of 2017, put the super testmode.key on a SD or usb, put that in, and it should boot to testmode. Go into file maintenance, and remove the file:
USER\SYSTEM\Download\StartKnd.log. This will kick the unit out of upgrade mode, and should restart into regular mode on next power up (remember to remove the TestMode SD).
Another possibility is to add or remove /USER/PRG.FLG to tell the system to use the other program files.

Assuming the F-series is like the US Z series, it requires moving an unused wire in the harness (or adding new wire), then grounding that one. If you can watch a DVD while driving (not a good idea except for testing), it is installed. It is possible that the wire is loose - either in the harness or the ground connection. That has been known to cause intermittent problems.
The 2017 EU maps are here - New 2017 Release F20BT F30BT F40Bt F920BT F930BT F840BT Etc. It has BT version 3.32.
Since you have an F920bt, you'll need to replace the CardInfo.cif file. The one I attached should work. If the update doesn't start, you can create your own reading through that long thread.
CARDINFO.cif